1. Field Of The Invention
This invention relates generally to tire pressure sensing and signalling devices and more particularly is directed towards a new and improved pressure responsive acoustical valve for use in a tire pressure reporting system.
2. Description Of The Prior Art
In U.S. Pat. Nos. 3,489,998, 3,699,264 and 3,738,308 there are disclosed tire pressure alarm systems for motor vehicles wherein a change in the tire pressure beyond predetermined levels produces an acoustical signal used to actuate an alarm and warn the operator. In general, these systems employ acoustical valves fitted to the wheel and which respond to tire pressure changes by generating acoustical signals whenever the tire pressure exceeds predetermined limits pre-set in the valves. Acoustical pick-up devices in the form of microphones are positioned in close proximity to the wheel to respond to the acoustical signal. Warning devices in the form of lights, buzzers or the like are coupled to the microphone through signal processing circuitry which includes a memory for storing information with respect to a pressure event during the absence of the operator.
It is an object of the present invention to provide improvements in tire pressure reporting valves of the foregoing type. A more specific object is to provide a tire pressure reporting valve in which the moving parts function with minimal friction, low hysteresis and high precision with respect to pressure levels. Another object of this invention is to provide a valve of the above type having a positive pressure sealing action during normal operation. A further object of this invention is to provide a tire pressure monitoring valve and acoustical generator of a highly efficient nature for use with an acoustical sensing system mounted to the vehicle.